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The data provided below is the result of laboratory analysis of water samples collected by the Department of Primary Industry and Resources (DPIR) Environmental Monitoring Unit (EMU). Following is a brief description of the EMU and the functions it performs for the department.
Environmental Monitoring Unit
EMU is a specialist unit whose team members have extensive practical experience in water sampling and monitoring techniques. EMU role is to provide the department with high quality monitoring date for surface and groundwater across all mine sites in the Northern Territory (NT). In addition EMU provides training and advice to operators on correct sampling procedures. Data collected by EMU also serves as a QA/QC check against data collected and provided to the department by mine operators. EMU are also involved in investigations into cases of potential environmental harm when required. EMU has a range of specialised equipment to enable it to operate effectively in the field included a Laboratory Truck (designed by EMU) that allows state of the art processing of water samples in the field. The unit spends extensive amounts of time in the field, in 2012 team members spent approximately 620 days in the field; it currently has five team members.
Analysis of the data collected by EMU allows for:
- monitoring of mine site environmental performance
- verification of the mining company supplied environmental data
- if required, intervention and notification in the event of potential environmental impacts relating to mining activities.
The EMU’s core activities include:
- collecting samples from operational and legacy mine sites in accordance with approved monitoring programs
- deploying automated loggers to complement monitoring programs
- collecting biological data to complement water monitoring programs at strategic sites
- undertaking base-line monitoring of new mining operations to enable development of an appropriate monitoring program
- undertaking investigations as required by Mining Officers.
EMU have a purpose built Lab Truck that assists in the collection of quality water samples for analysis. This current version of the Lab Truck is as a result of 20 years developmental research, into the best practice ground and surface water sample collection.
The use of the Lab Truck enables laboratory quality sample preparation and sample preservation, in a clean controlled environment. Samples collected using the Lab Truck are filtered, and preserved to accepted best practice standards, to maximise the holding times and sample quality. EMU preform simple analysis in the field, such as alkalinity measurements that would otherwise deteriorate from extended holding times. All field measurements are carried out on instruments that are checked against laboratory quality instruments and standards prior to leaving the Darwin base and are check calibrated daily, and re-checked after the days field work to ensure they remain within the standards set.
Some of the equipment and facilities included with in the Lab Truck are;
- 40lt tank of demineralised water that is maintained at the required purity by an ion exchange and filter system to polish the water at the point of use
- a 120lt Fridge to store samples at 4°C and 110lt freezer capable of freezing samples within a couple of hours after collection to ensure sample quality is maintained
- a vacuum filtration system for filtering surface water samples, and a pressure filtration system for filtering groundwater samples enabling these samples to be filtered prior to exposure to oxygen
- the capacity to safely store ultra-pure acids for preservation of samples
- air-conditioning to help preserve a clean work environment by positive pressure
- storage of equipment and sample containers for field trips lasting more than two weeks.
The Lab Truck ensures sample preparation integrity, by providing the following benefits:
- samples are prepared in a contamination free environment
- physical chemistry from surface water samples is taken as soon as possible after collection (usually within minutes)
- groundwater is only sampled when stable water chemistry is reached from a closed cell
- surface water samples are filtered and acidified within the hour they are collected
- groundwater samples are filtered prior to being exposed to the atmosphere, and acidified within minutes of the sample being taken
- cool/air-conditioned unit to reduce heat stress and sample contamination.